Dual direction axial fan

ABSTRACT

A dual direction axial fan is provided and includes a body having a retention assembly and being rotatable in first or second directions, a blade being retained by the retention assembly such that the airfoil section extends from the body with the blade assuming first, second or third orientations and a switching mechanism coupled to the retention assembly to urge the blade to assume the second or the third orientation when the body rotates in the first or the second direction, respectively.

BACKGROUND OF THE INVENTION

The subject matter disclosed herein relates to a dual direction axial fan and, more particularly, to a dual direction axial fan having a switching mechanism.

Industrial environments often employ totally enclosed, fan cooled (TEFC) motors. These motors are only slightly more expensive than open motors yet offer protection against common hazards. They are constructed with a small fan on the rear shaft of the motor, which is usually covered by a housing. This fan draws air over the motor fins and removes excess heat to cool the motor. The motor is dust tight and has a moderate water seal as well.

In many rotating machines, it is necessary to use radial fans even though axial fans would be the ideal choice. The reason for this is that the motors are designed to rotate in both directions and, normally, single axial fans do not work in both directions. Thus, the use of radial fans represents a compromise on performance.

BRIEF DESCRIPTION OF THE INVENTION

According to one aspect of the invention, a dual direction axial fan is provided and includes a body having a retention assembly and being rotatable in first or second directions, a blade being retained by the retention assembly such that the airfoil section extends from the body with the blade assuming first, second or third orientations and a switching mechanism coupled to the retention assembly to urge the blade to assume the second or the third orientation when the body rotates in the first or the second direction, respectively.

According to another aspect of the invention, a dual direction axial fan is provided and includes a body having a blade retention assembly and being rotatable about a centerline thereof in first or second directions, a blade having an airfoil section and a shank, the shank being retained in the body by the blade retention assembly such that the airfoil section extends from the body with the blade assuming first, second or third orientations and a switching mechanism coupled to the blade retention assembly to urge the blade to assume the second or the third orientation when the body rotates in the first or the second direction, respectively.

According to yet another aspect of the invention, a dual direction axial fan is provided and includes a hub, which is rotatable about a centerline thereof, having an annular sidewall and an endplate at a first end of the annular sidewall through which a u-shape hole is defined, a cover, through which a radial holes defined, and which is fittable to a second end of the sidewall such that the cover occupies and moves between first, second or third positions, a blade having a shank to extend through a radial hole defined in the sidewall, the blade being configured to assume first, second or third orientations, a sleeve, which is tightly fittable about the shank of the blade, a first elastic element anchored on the hub and engageable with the sleeve, a pin and nut combination to extend through a corresponding pair of the u-shaped hole and the radial hole and a second elastic element to bias the pin and nut combination toward a position whereby the cover is constrained in the second or the third position when the hub rotates in the first or the second direction, respectively.

These and other advantages and features will become more apparent from the following description taken in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWING

The subject matter, which is regarded as the invention, is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features, and advantages of the invention are apparent from the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is an enlarged cutaway side view of a dual direction axial fan;

FIG. 2 is a side view of the duel direction axial fan of FIG. 1 with the blades in a first orientation;

FIG. 3 is a side view of the duel direction axial fan of FIG. 1 rotating in a first direction with the blades in a second orientation;

FIG. 4 is a side view of the duel direction axial fan of FIG. 1 rotating in a second direction with the blades in a third orientation;

FIG. 5 is a perspective view of a hub with a u-shaped through hole of the dual direction axial fan of FIG. 1;

FIG. 6 is an axial view of a cover of the hub of FIG. 2 with radial holes;

FIG. 7 is an axial view of a pin and nut combination in a first position when the axial fan is not rotating;

FIG. 8 is an axial view of a pin and nut combination in a second position when the axial fan is rotating in a first direction; and

FIG. 9 is an axial view of a pin and nut combination in a third position when the axial fan is rotating in a second direction.

The detailed description explains embodiments of the invention, together with advantages and features, by way of example with reference to the drawings.

DETAILED DESCRIPTION OF THE INVENTION

In accordance with an aspect of the invention, an axial fan is provided that can be operated in first and second rotational directions. For the purposes of the detailed description below, an axial fan is a fan that blows fluid in axial directions. Normally, axial fans have blades with a given orientation that are rotated in one directed such that fluid is blown in only one direction. In the present invention, however, the blade orientation can be switched and the axial fan can be rotated in first and second directions to blow air in first and second axial directions. The axial fan can be used in many applications it would be otherwise necessary to employ inefficient radial fans. In order to achieve this, the axial fan includes a switching mechanism that adjusts the blades in both the directions of rotation. The switching mechanism is a combination of a rack and pinion mechanism and a centrifugal switch mechanism.

With reference to FIG. 1, a dual direction axial fan 10 is provided. The axial fan 10 includes a body 20. The body 20 is substantially cylindrical and is formed to define an interior therein in which a blade retention assembly 21 is retained. The body 20 is also rotatable about a centerline 22 thereof in first or second opposite directions. A rotor (not shown) may be provided along the centerline 22 to provide motive force for driving the body 20 to rotate in the first and second directions. The axial fan 20 further includes a blade 30 and a switching mechanism 40. The blade 30 includes an airfoil section 31, having an airfoil shape, and a shank 32 to which the airfoil section 31 is connected. The shank 32 is retained in the interior of the body 20 by the blade retention assembly 21 such that the airfoil section 31 extends from the body 20 in a radial direction with the blade 30 assuming first, second or third orientations. The switching mechanism 40 is coupled to the blade retention assembly 21 and configured to urge the blade 30 to assume the second or the third orientations when the body 20 rotates in the first or the second direction, respectively.

With reference to FIGS. 2, 3 and 4, the blade retention assembly 21, the blade 30 and the switching mechanism 40 are each correspondingly plural in number and arrayed about the centerline 22 of the body 20 with substantially uniform separation. With this construction, when the body 20 is not rotating, the blades 30 as retained by the blade retention assemblies 21 are permitted by the switching mechanisms 40 to assume the first orientation, as shown in FIG. 2. When the body 20 rotates in the first direction, the switching mechanisms 40 cause the blades 30 to assume the second orientation, as shown in FIG. 3, to blow air in a first axial direction. By contrast, when the body 20 rotates in the second direction, the switching mechanisms 40 cause the blades 30 to assume the third orientation, as shown in FIG. 4, to blow air in a second axial direction opposite the first axial directions.

Although described above as being plural in number and arrayed about the body 20, the blade retention assembly 21, the blade 30 and the switching mechanism 40 will be hereinafter described as single features for the purpose of clarity and brevity. This is to be understood as being merely exemplary and not a limiting embodiment of the invention.

With reference back to FIG. 1 and with further reference to FIGS. 5 and 6, the switching mechanism 40 includes a rack and pinion mechanism 41 and a centrifugal switch mechanism 42, which is operably coupled to the rack and pinion mechanism 41.

As shown in FIG. 5, the body 20 includes a hub 201 having an annular sidewall 202 with first and second opposite ends and an end plate 203 at the first end of the annular sidewall 202. A central aperture 204 may be formed through the end plate 203 for fitting the body 20 onto a rotor and an array of u-shaped (or “reversed smile”) pin holes 205 are defined about the central aperture 204 with one pin hole 205 for each blade 30. A radial through hole 206 may be defined in the annular sidewall 202 through which the shank 32 of the blade 30 extends in a radial direction. The blade retention assembly 21 includes a portion 207 of the annular sidewall 202 at which the radial through hole 206 is defined and a first elastic element 208, such as a spring, which is anchored on the hub 201 and coupled to the shank 32 of the blade 30. In accordance with an embodiment, a sleeve 209 is provided to be tightly fittable about the shank 32 of the blade 30 and engageable with the first elastic element 208.

As shown in FIG. 6, the body 20 further includes a cover 210 that may be snap fit onto the second end of the annular sidewall 202. The snap fit provides for clearance between the hub 201 and the cover 210 allowing for relative rotational movement of the hub 201 and the cover 210 between first, second or third positions. The first, second and third positions are respectively associated with the first, second and third orientations of the blade 30. The cover 210 is plate shaped and has a body 211 through which radial pin holes 212 are defined in a number and configuration that is in agreement with the pin holes 205.

The centrifugal switch mechanism 42 includes an array of pin and nut combinations 220 and a second elastic element 230. Each pin and nut combination 220 includes an elongate pin 221, which extends through a corresponding pair of a pin hole 205 and a radial pin hole 212, and a nut 222 that locks the cover 210 onto the hub 201 in the axial direction. The second elastic element 230 may be a spring with a hook at each end to be respectively anchored to the hub 201 and the pin 221. The second elastic element 230 biases each pin and nut combination 220 toward a position whereby the cover 210 is constrained in the first, second or third position when the body 20 is not rotating or when the body 20 rotates in the first or the second direction, respectively.

With reference back to FIG. 1 and with further to FIGS. 1, 7, 8 and 9, the various positions of each of the pin and nut combinations 220 are illustrated. As shown in FIG. 7, with the body 20 not rotating, the pin and nut combination 220 is biased radially inwardly by the second elastic element 230 to occupy a position at a central point along the base of the pin hole 205 and at a radially inward point along the radial pin hole 212. This constrains the cover 210 at the first position. As shown in FIG. 8, with the body 20 rotating in the first direction, the hub 201 trails the rotation and the cover 210 is static due to inertia. Thus, the hub 201 and the cover 210 demonstrate relative rotational movement in a first direction and the pin and nut combination 220 is forced radially outwardly against the bias of the second elastic element 230 by centrifugal force toward radially outward points of one side of the pin hole 205 (i.e., the side trailing the rotation) and the radial pin hole 212. This constrains the cover 210 at the second position. By contrast, as shown in FIG. 9, with the body 20 rotating in the second direction, the hub 201 again trails the rotation with the cover 210 static such that the hub 201 and the cover demonstrate relative rotational movement in a second direction and the pin and nut combination 220 is forced radially outwardly against the bias of the second elastic element 230 by centrifugal force toward radially outward points of the other side of the pin hole 205 and the radial pin hole 212. This constrains the cover 210 at the third position.

The rack and pinion mechanism 41 includes a gear 240 to which the shank 32 of the blade 30 is coupled and a rack 241 of the cover 210 to rotatably engage with the gear 240. The gear 240 includes a ring portion 242, which is tightly connected to the shank 32 of the blade 30 and teeth 243 extending from the ring portion 242 to rotatably engage with the rack 241 of the cover 210. Since the gear 240 moves with the hub 201, the relative rotational movement in the first and second directions between the hub 201 and the cover 210 causes the gear 240 to rotate about a longitudinal axis of the shank 32 of the blade 30. Thus, when the cover 210 is rotated toward and constrained in the second or the third position, the gear 240 rotates in respectively opposite directions as well. Since the ring portion 242 is tightly connected to the shank 32, the rotation of the gear 240 causes corresponding rotation of the blade 30 into the second or the third orientations, respectively, in accordance with a rotational direction of the body 20.

While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the spirit and scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the invention may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims. 

1. A dual direction axial fan, comprising: a body having a retention assembly and being rotatable in first or second directions; a blade being retained by the retention assembly such that the airfoil section extends from the body with the blade assuming first, second or third orientations; and a switching mechanism coupled to the retention assembly to urge the blade to assume the second or the third orientation when the body rotates in the first or the second direction, respectively.
 2. The dual direction axial fan according to claim 1, wherein the retention assembly, the blade and the switching mechanism are each correspondingly plural in number and arrayed about the body with uniform separation.
 3. The dual direction axial fan according to claim 1, wherein the switching mechanism comprises: a rack and pinion mechanism; and a centrifugal switch mechanism operably coupled to the rack and pinion mechanism.
 4. The dual direction axial fan according to claim 3, wherein the body comprises: a hub having an annular sidewall and an end plate at a first end thereof, through which u-shaped pin holes are defined; and a cover through which radial pin holes are defined, the cover being fittable to a second end of the sidewall such that the cover occupies and moves between first, second or third positions associated with the first, second and third orientations, respectively.
 5. The dual direction axial fan according to claim 4, wherein a radial through hole through which a shank of the blade extends is defined through the sidewall, the blade retention assembly comprising: a portion of the sidewall at which the radial through hole is defined; and a first elastic element anchored on the hub and coupled to the shank of the blade.
 6. The dual direction axial fan according to claim 5, further comprising a sleeve, which is tightly fittable about the shank of the blade and which is engageable with the first elastic element.
 7. The dual direction axial fan according to claim 5, wherein the centrifugal switch mechanism comprises: an array of pin and nut combinations, each pin and nut combination being configured to respectively extend through a corresponding pair of a u-shaped pin hole and a radial pin hole; and a second elastic element to bias each pin and nut combination toward a position whereby the cover is constrained in the second or the third position when the body rotates in the first or the second direction, respectively.
 8. The dual direction axial fan according to claim 7, wherein the rack and pinion mechanism comprises: a gear to which the shank of the blade is coupled; and a rack of the cover to rotatably engage with the gear.
 9. A dual direction axial fan, comprising: a body having a blade retention assembly and being rotatable about a centerline thereof in first or second directions; a blade having an airfoil section and a shank, the shank being retained in the body by the blade retention assembly such that the airfoil section extends from the body with the blade assuming first, second or third orientations; and a switching mechanism coupled to the blade retention assembly to urge the blade to assume the second or the third orientation when the body rotates in the first or the second direction, respectively.
 10. The dual direction axial fan according to claim 9, wherein the blade retention assembly, the blade and the switching mechanism are each correspondingly plural in number and arrayed about the centerline of the body.
 11. The dual direction axial fan according to claim 9, wherein the switching mechanism comprises: a rack and pinion mechanism; and a centrifugal switch mechanism operably coupled to the rack and pinion mechanism.
 12. The dual direction axial fan according to claim 11, wherein the body comprises: a hub having an annular sidewall and an end plate at a first end thereof, through which u-shaped pin holes are defined; and a cover through which radial pin holes are defined, the cover being fittable to a second end of the sidewall such that the cover occupies and moves between first, second or third positions associated with the first, second and third orientations, respectively.
 13. The dual direction axial fan according to claim 12, wherein a radial through hole through which the shank of the blade extends is defined through the sidewall.
 14. The dual direction axial fan according to claim 13, wherein the blade retention assembly comprises: a portion of the sidewall at which the radial through hole is defined; and a first elastic element anchored on the hub and coupled to the shank of the blade.
 15. The dual direction axial fan according to claim 14, further comprising a sleeve, which is tightly fittable about the shank of the blade and which is engageable with the first elastic element.
 16. The dual direction axial fan according to claim 12, wherein the u-shaped pin holes are defined about an axial aperture through the end plate.
 17. The dual direction axial fan according to claim 12, wherein the centrifugal switch mechanism comprises: an array of pin and nut combinations, each pin and nut combination being configured to respectively extend through a corresponding pair of a u-shaped pin hole and a radial pin hole; and a second elastic element to bias each pin and nut combination toward a position whereby the cover is constrained in the second or the third position when the body rotates in the first or the second direction, respectively.
 18. The dual direction axial fan according to claim 17, wherein the rack and pinion mechanism comprises: a gear to which the shank of the blade is coupled; and a rack of the cover to rotatably engage with the gear.
 19. The dual direction axial fan according to claim 18, wherein the gear comprises: a ring portion connected to the shank of the blade; and teeth extending from the ring portion to rotatably engage with the rack of the cover.
 20. A dual direction axial fan, comprising: a hub, which is rotatable about a centerline thereof, having an annular sidewall and an endplate at a first end of the annular sidewall through which a u-shape hole is defined; a cover, through which a radial hole is defined, and which is fittable to a second end of the sidewall such that the cover occupies and moves between first, second or third positions; a blade having a shank to extend through a radial hole defined in the sidewall, the blade being configured to assume first, second or third orientations; a sleeve, which is tightly fittable about the shank of the blade; a first elastic element anchored on the hub and engageable with the sleeve; a pin and nut combination to extend through a corresponding pair of the u-shaped hole and the radial hole; and a second elastic element to bias the pin and nut combination toward a position whereby the cover is constrained in the second or the third position when the hub rotates in the first or the second direction, respectively. 